Numerical Analysis of Ultra-High Frequency Wire Bonding

For commercial applications, it is assumed the evolution of ultrasonic wire bonding process frequencies will progress from the currently used frequency ranges to higher frequency ranges. A finite elemente frequency analysis is reported for a typical ball bonding application. This analysis is extended to ultrasonic frequencies between 1 and 700 kHz. Based on simulations, the next higher range suitable for industrial wire bonding is suggested to be between 390 and 410 kHz. In this range, the process is more sensitive to the capillary geometry. Between 27% and 76% less ultrasonic horn amplitude is required for successful bonding, depending on the capillary type used. Underpad stress

is found smaller. The suggested frequency range has the potential to improve the low stress, low temperature, and low bond time performance of the bonding process. The results serve as guidelines for future designs of ultra-high frequency transducers, capillaries, and bonding processes.